Talk to Mr. Kim in City Wok to start this quest and receive the Tower of Peace key. As soon as you enter the tower, you'll be fighting off some mongol kids. Defeat them then shoot the pulley to bring down the ladder.
Defeat all kids in the second floor and loot the Mongorian Bow from them. Shoot the Chinpokomon hanging on the right side then get the hidden treasure key behind the busted part of the wall on the eastern side. The chest is located to the left, above the gong. You need to circle around through the busted wall to get it.
Head to the next floor and you'll find a dragon door. Defeat all the mongol kids then shoot off the hanging dragon tail. Pick it up and place it on the missing part of the left door. Shoot both of the dragon heads to open the path. Save your game and continue upstairs.
You'll be fighting the Mongolian Horde. They only share one life bar so don't worry about concentrating your attacks. Inflict them with additional status ailments like Burning and block their attacks. After defeating them, return to Mr. Kim to claim your reward.